Synthetic biomaterials have become increasingly important in biomedical applications. Calcium-based materials, for example, have been used for the restoration of bone and dental tissue function. Various crystalline phases of calcium phosphate (“Ca—P”), such as hydroxyapatite Ca5(P04)30H, tricalcium phosphate (Ca3(P04)2, “TCP”), amorphous calcium phosphate (Ca3(P04)2, “ACP”), octacalcium phosphate (Ca8H2(P04)6.5H20, “OCP”), tetracalcium phosphate and carbonated or fluoridated apatite have been used in bone and dental implants in many forms for decades. Dense sintered hydroxyapatite has been used in middle ear implantation. Calcium phosphate cement has been used in filling bone defects in dental and orthopedic surgery. Calcium phosphate coatings on metal implants have been shown to encourage direct bone deposition on the implants, thereby forming a strong bond between implants and bone tissues.
For repair of bone defects, engineered matrices and scaffolds should not only provide mechanical support for cell growth, but should also mimic the extracellular matrix (“ECM”) of the desired tissue. However, current polymeric nanofibers do not adequately mimic the natural in vivo three-dimensional morphology and environment experienced by bone and dental cells. Those polymeric nanofibers that do employ calcium phosphate do so only in the form of amorphous calcium phosphate mixed into the primarily polymer based nanofibers. Such polymeric nanofibers do not mimic the highly crystalline calcium phosphate environment experienced by bone and dental cells. Moreover, currently existing microfibers are too large to adequately mimic the ECM of the desired tissue. However, to date, matrices comprising calcium phosphate nanofibers in any crystalline phases, particularly those in randomly-dispersed fibrous networks that mimic the ECM of naturally occurring bone and/or dental cells, remain elusive. Thus, there is a continuing need to develop and improve nano-scale fibrous structures comprising primarily calcium phosphate that can be used for bone and dental tissue repair and regeneration.